Design of a solar-assisted mechanical vapor compression (MVC) desalination unit for remote areas in the UAE

Scarcity of fresh water in the United Arab Emirates is a challenging problem particularly for small isolated communities to which water and electricity are difficult and/or costly to transport. Meanwhile, solar radiation in the UAE is exceptionally high around the year, which represents an environmentally safe source for power generation. In the meantime, mechanical vapor compression is an attractive technology suitable for the design of small capacity desalination units with a reasonable degree of mobility and compactness. An autonomous small capacity desalination unit that depends solely on solar power is not practically feasible. This is due to the excessive number of batteries required to back up the system during night time and blackout hours. In view of these facts, we find that a diesel-solar-assisted MVC desalination system represents an optimal solution to provide small communities at remote areas with fresh water while generating enough power for the operators housing and plant operation with minimal impact on the environment. This paper outlines a detailed model for the design of a hybrid solar-diesel powered MVC unit with a fresh water capacity of 120 m3/d. Preliminary design of a photovoltaic array to furnish the power required to drive the desalination unit, the control room and the housing of operators is illustrated. Sensitivity analysis of the main cost elements of the plant to design parameters is presented. Finally, the environmental impact of the solar assisted unit is illustrated with respect to CO2 emissions and atmospheric oxygen consumption.